The present invention relates to a fuel injector.
A fuel injector which may be electromagnetically actuated is described in German Published Patent Application No. 196 37 103, in which a swirl-generating arrangement is provided downstream from a valve seat. The swirl-generating arrangement is shaped in such a manner that at least two streams may be created from the fuel which run radially offset with respect to one another while mutually enveloping or enclosing one another and which have different directional orientations. The arrangement for creating the injection jet composed of an inner and an outer stream having different directional orientations may be quite complicated and relatively expensive to manufacture on account of the flow blades which serve as guide elements and the multilayer swirl mountings on a perforated disk. The swirl-generating arrangement may be configured in such a manner that either a swirling solid conical jet or a swirling hollow conical jet exits from the fuel injector.
The technique referred to as multilayer metal plating for the manufacture of perforated disks which may be particularly suited for use in fuel injectors has already been described in German Published Patent Application 196 07 288. This principle for manufacturing disks by multiple metal electrodeposition of various structures one on top of the other to produce a one-piece disk may be expressly included in the disclosure content of the present invention. Microelectrodeposition in multiple planes or layers may also be used to manufacture the swirl disks according to the present invention.
A fuel injector according to an example embodiment of the present invention may achieve a high-quality atomization of a fuel to be injected. Using a fuel injector according to an example embodiment of the present invention, a double swirl may be generated in a swirl disk which may be integrated into the fuel injector, the double swirl generation occurring in the same direction in the fluid so that a finely atomized, hollow conical spray jet composed of two hollow conical lamellae concentrically arranged one inside the other may be injected. As a result, among other things, the exhaust emissions from the internal combustion engine may be reduced and likewise the fuel consumption may be decreased in a fuel injector of an internal combustion engine.
The swirl-generating element may be configured in the shape of a multilayer swirl disk so that a double swirl may be created. The swirl disk may be manufactured using the technique referred to as multilayer metal plating. On account of their metallic construction, such swirl disks may be break-resistant and easy to install. Use of multilayer metal plating may allow high freedom in the configuration, since the contours of the opening areas (inlet area, swirl channels, swirl chambers, outlet openings) in the swirl disk may be freely selected. Compared to silicon discs in particular, whose crystal axes may strictly dictate the contours which may be achieved (truncated pyramids), this flexible shaping may be desirable.
In comparison to the manufacture of silicon disks in particular, metal deposition may provide a large variety of usable materials. Many varied types of metals having different magnetic properties and hardnesses may be used in microelectrodeposition for the manufacturing of swirl disks.
The swirl disks may be constructed using five layers by performing four or five, for example, electrodeposition steps for multilayer metal plating. The upstream layer represents a top layer which may completely cover the swirl chamber of a first middle swirl-generating layer. The swirl-generating layer is formed from a plurality of material areas which on account of their contouring and geometric position with respect to one another may determine the contours of the swirl chambers and swirl channels. This may also apply to a second middle swirl-generating layer which may be separated from the first swirl-generating layer by a middle forwarding layer, but which may be in hydraulic connection with the first swirl-generating layer via flow openings in the forwarding layer. A swirling portion of the flow as well as a portion of the flow without swirl and independent of the swirling portion of the flow enter the forwarding layer, the portion of the flow without swirl being transmitted into the second swirl-generating layer for imparting swirl. The individual layers may be successively applied to one another by electrodeposition, without separation areas or joint areas, in such a manner that they represent a material which may be homogeneous throughout. In this regard, the term xe2x80x9clayersxe2x80x9d is intended as a conceptual aid.
The swirl disc may be provided with at least two, or alternatively four, swirl channels for each swirl-generating layer for imparting a swirl component to the fuel. The material areas may have very different shapes, corresponding to the desired contouring.